The math suggest you have 468, the last 10 points might not be counted because a question or an answer you had a vote on was hidden. Anyway, the math is:
20 starting points + 30 points from selecting Best Answers + 200 points from being selected Best Answer + 280 points from upvotes - 60 points from downvotes - 2 points from downvoting someone.
So: 20+30+200+280-60-2=468. Its most likely because you have a vote not listed because you have had a question or answer hidden. Don't forget to add points from selecting Best